The Online Library of Knowledge

Energy

You are here: Science > Energy

Energy

A geyser, caused by geothermal energyA geyser, caused by geothermal energy Energy is the ability to make things happen, cause changes and carry out work. Any change anywhere in the Universe, from a tiny meteorite hitting a planet to an exploding star, means that energy is at work. In daily life, energy is all around us in many different forms. Light travels through space, most gases, and some liquids and solids. Sound energy travels through all gases, liquids and solids as pressure waves. Heat is a form known as thermal energy. Geothermal energy from hot rocks deep in the Earth causes geysers, jets of hot water and steam. Movement or motion is another form of energy; it is called kinetic energy. Other forms include electricity, chemical energy and nuclear energy. Perhaps surprisingly, mass is another form of energy.

 
Different forms of energyDifferent forms of energy
Potential energy is stored in the bow's bent arms.Potential energy is stored in the bow's bent arms.Click to play video

Potential energy

Objects even have energy because of their place, position or chemical composition. This is called potential energy. A boulder on a hilltop has potential energy because gravity tries to pull it down. As the boulder begins to roll its potential energy changes into kinetic energy. An explosive like dynamite is packed with potential energy.

This can be released as a huge explosion when the chemicals of which it is made of react together. This kind of potential energy is sometimes called chemical energy (see below).
 

Dark energy is a kind of energy that we can neither see nor feel. It is found in space, and thought to be responsible for accelerating the expansion of the Universe. Dark energy accounts for 73% of all the energy in the Universe.

© 2020 Q-files Ltd. All rights reserved. Switch to Mobile